[Mahler9th]

Bruce Anderson's 911 book has some perspective on various exhausts. Includes some dyno results. Worthwhile reading.

Quite a few folks with track, race and mixed use cars have used a variety of approaches. There is also a range of sound requirements at tracks throughout the country, and localized solutions abound.

Simply adding turndowns, et cetera can be great for some situations, but they are not a panacea.

More generalized solutions with specs like "I want to be able to make 92 dB exhaust sound at Laguna Seca" can be easier to find.

In that example, yes, induction noise can also be an issue. For example, when the 993 TT first came out, we had one at a Laguna event that could not make sound due to induction noise. Stock car with stock induction and exhaust.

The sound booth at Laguna is just after the exiit of turn 5, and so the driver just lifted and short shifted. But at Laguna in those days, the testing protocol allowed them to move to different places on the track.

It pays to consider requirements the car will face, and to tap into localized resources that have been there and done that.

Quiet Horsepower has a lot of institutional knowledge from situations all over the country, and it happens a bunch of this is with respect to air cooled Porsche applications.